Number Theory: Unique Numbers

  1. Does anyone know of a reference work that lists natural numbers with unique properties? Like 26, for example, being the only natural number sandwiched between a square (25) and a cube (27). Does such a reference book exist?

  2. jcsd
  3. micromass

    micromass 20,059
    Staff Emeritus
    Science Advisor
    Education Advisor

  4. Thanx Micro, I was aware of certain Wikipedia articles; what I specifically am looking for though, is a systematic reference work of all know unique numbers. I could not find something resembling this on the net...
  5. mfb

    Staff: Mentor

    It depends a lot on the things you consider as unique properties. Every number has unique properties, but most of them are boring ("is the only number x where x-23 and x-24 are primes" is another one for 26). Random collections are the best things you can find.
  6. that a trivial uniqueness quality that you just mentioned for 26? Doesn't seem so to me but then I am the layman here...

    Can one somehow 'define' mathematical triviality for such unique qualities I wonder...

  7. mfb

    Staff: Mentor

    It is trivial in the way that "x-23 prime and x-24 prime" requires two primes with a difference of just 1, and 2 and 3 are the only primes that satisfy this.
    You can set this up for every integer.
  8. Yes, if course...silly me...
  9. Curious3141

    Curious3141 2,943
    Homework Helper

  10. Thanx Curious, exactly the type of thing I was looking for, thanx a million...I kept repeating "unique" in all my Google searches, so there you go...a little variety is always good...

  11. mfb

    Staff: Mentor

    Note that not all those entries are unique, and some of them just reflect our limited knowledge. And some are... pointless.

    "151 is a palindromic prime." - true, but there are 7 smaller palindromic primes and probably infinitely more larger ones.
    "146 = 222 in base 8." - so what?
  12. Thanx for the clarification mob...funny I would have thought that a compendium of numbers with unique characteristics would be a given in number theory...quite surprised that it's so difficult to find...

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